Maiden Lane, no less than Wall Street, was deeply interested in the radium case. In fact, it seemed that one case in this section of the city led to another.

Naturally, the Star and the other papers made much of the capture of Denison. Still, I was not prepared for the host of Maiden Lane cases that followed. Many of them were essentially trivial. But one proved to be of extreme importance.

"Professor Kennedy, I have just heard of your radium case, and I—I feel that I can—trust you."

There was a note of appeal in the hesitating voice of the tall, heavily veiled woman whose card had been sent up to us with a nervous "Urgent" written across its face.

It was very early in the morning, but our visitor was evidently completely unnerved by some news which she had just received and which had sent her posting to see Craig.

Kennedy met her gaze directly with a look that arrested her involuntary effort to avoid it again. She must have read in his eyes more than in his words that she might trust him.

"I—I have a confession to make," she faltered.

"Please sit down, Mrs. Moulton," he said simply. "It is my business to receive confidences—and to keep them."

She sank into, rather than sat down in, the deep leather rocker beside his desk, and now for the first time raised her veil.

Antoinette Moulton was indeed stunning, an exquisite creature with a wonderful charm of slender youth, brightness of eye and brunette radiance.

I knew that she had been on the musical comedy stage and had had a rapid rise to a star part before her marriage to Lynn Moulton, the wealthy lawyer, almost twice her age. I knew also that she had given up the stage, apparently without a regret. Yet there was something strange about the air of secrecy of her visit. Was there a hint in it of a disagreement between the Moultons, I wondered, as I waited while Kennedy reassured her.

Her distress was so unconcealed that Craig, for the moment, laid aside his ordinary inquisitorial manner. "Tell me just as much or just as little as you choose, Mrs. Moulton," he added tactfully. "I will do my best."

A look almost of gratitude crossed her face.

"When we were married," she began again, "my husband gave me a beautiful diamond necklace. Oh, it must have been worth a hundred thousand dollars easily. It was splendid. Everyone has heard of it. You know, Lynn—er—Mr. Moulton, has always been an enthusiastic collector of jewels."

She paused again and Kennedy nodded reassuringly. I knew the thought in his mind. Moulton had collected one gem that was incomparable with all the hundred thousand dollar necklaces in existence.

"Several months ago." she went on rapidly, still avoiding his eyes and forcing the words from her reluctant lips, "I—oh, I needed money—terribly."

She had risen and faced him, pressing her daintily gloved hands together in a little tremble of emotion which was none the less genuine because she had studied the art of emotion.

"I took the necklace to a jeweler, Herman Schloss, of Maiden Lane, a man with whom my husband had often had dealings and whom I thought I could trust. Under a promise of secrecy he loaned me fifty thousand dollars on it and had an exact replica in paste made by one of his best workmen. This morning, just now, Mr. Schloss telephoned me that his safe had been robbed last night. My necklace is gone!"

She threw out her hands in a wildly appealing gesture.

"And if Lynn finds that the necklace in our wall safe is of paste—as he will find, for he is an expert in diamonds—oh—what shall I do? Can't you—can't you find my necklace?"

Kennedy was following her now eagerly. "You were blackmailed out of the money?" he queried casually, masking his question.

There was a sudden, impulsive drooping of her mouth, an evasion and keen wariness in her eyes. "I can't see that that has anything to do with the robbery," she answered in a low voice.

"I beg your pardon," corrected Kennedy quickly. "Perhaps not. I'm sorry. Force of habit, I suppose. You don't know anything more about the robbery?"

"N—no, only that it seems impossible that it could have happened in a place that has the wonderful burglar alarm protection that Mr. Schloss described to me."

"You know him pretty well?"

"Only through this transaction," she replied hastily. "I wish to heaven
I had never heard of him."

The telephone rang insistently.

"Mrs. Moulton," said Kennedy, as he returned the receiver to the hook, "it may interest you to know that the burglar alarm company has just called me up about the same case. If I had need of an added incentive, which I hope you will believe I have not, that might furnish it. I will do my best," he repeated.

"Thank you—a thousand times," she cried fervently, and, had I been Craig, I think I should have needed no more thanks than the look she gave him as he accompanied her to the door of our apartment.

It was still early and the eager crowds were pushing their way to business through the narrow network of downtown streets as Kennedy and I entered a large office on lower Broadway in the heart of the jewelry trade and financial district.

"One of the most amazing robberies that has ever been attempted has been reported to us this morning," announced James McLear, manager of the Hale Electric Protection, adding with a look half of anxiety, half of skepticism, "that is, if it is true."

McLear was a stocky man, of powerful build and voice and a general appearance of having been once well connected with the city detective force before an attractive offer had taken him into this position of great responsibility.

"Herman Schloss, one of the best known of Maiden Lane jewelers," he continued, "has been robbed of goods worth two or three hundred thousand dollars—and in spite of every modern protection. So that you will get it clearly, let me show you what we do here."

He ushered us into a large room, on the walls of which were hundreds of little indicators. From the front they looked like rows of little square compartments, tier on tier, about the size of ordinary post office boxes. Closer examination showed that each was equipped with a delicate needle arranged to oscillate backward and forward upon the very minutest interference with the electric current. Under the boxes, each of which bore a number, was a series of drops and buzzers numbered to correspond with the boxes.

"In nearly every office in Maiden Lane where gems and valuable jewelry are stored," explained McLear, "this electrical system of ours is installed. When the safes are closed at night and the doors swung together, a current of electricity is constantly shooting around the safes, conducted by cleverly concealed wires. These wires are picked up by a cable system which finds its way to this central office. Once here, the wires are safeguarded in such manner that foreign currents from other wires or from lightning cannot disturb the system."

We looked with intense interest at this huge electrical pulse that felt every change over so vast and rich an area.

"Passing a big dividing board," he went on, "they are distributed and connected each in its place to the delicate tangent galvanometers and sensitive indicators you see in this room. These instantly announce the most minute change in the working of the current, and each office has a distinct separate metallic circuit. Why, even a hole as small as a lead pencil in anything protected would sound the alarm here."

Kennedy nodded appreciatively.

"You see," continued McLear, glad to be able to talk to one who followed him so closely, "it is another evidence of science finding for us greater security in the use of a tiny electric wire than in massive walls of steel and intricate lock devices. But here is a case in which, it seems, every known protection has failed. We can't afford to pass that by. If we have fallen down we want to know how, as well as to catch the burglar."

"How are the signals given?" I asked.

"Well, when the day's business is over, for instance, Schloss would swing the heavy safe doors together and over them place the doors of a wooden cabinet. That signals an alarm to us here. We answer it and if the proper signal is returned, all right. After that no one can tamper with the safe later in the night without sounding an alarm that would bring a quick investigation."

"But suppose that it became necessary to open the safe before the next morning. Might not some trusted employee return to the office, open it, give the proper signals and loot the safe?"

"No indeed," he answered confidently. "The very moment anyone touches the cabinet, the alarm is sounded. Even if the proper code signal is returned, it is not sufficient. A couple of our trusted men from the central office hustle around there anyhow and they don't leave until they are satisfied that everything is right. We have the authorized signatures on hand of those who are supposed to open the safe and a duplicate of one of them must be given or there is an arrest."

McLear considered for a moment.

"For instance, Schloss, like all the rest, was assigned a box in which was deposited a sealed envelope containing a key to the office and his own signature, in this case, since he alone knew the combination. Now, when an alarm is sounded, as it was last night, and the key removed to gain entrance to the office, a record is made and the key has to be sealed up again by Schloss. A report is also submitted showing when the signals are received and anything else that is worth recording. Last night our men found nothing wrong, apparently. But this morning we learn of the robbery."

"The point is, then," ruminated Kennedy, "what happened in the interval between the ringing of the alarm and the arrival of the special officers? I think I'll drop around and look Schloss' place over," he added quietly, evidently eager to begin at the actual scene of the crime.

On the door of the office to which McLear took us was one of those small blue plates which chance visitors to Maiden Lane must have seen often. To the initiated—be he crook or jeweler—this simple sign means that the merchant is a member of the Jewelers' Security Alliance, enough in itself, it would seem, to make the boldest burglar hesitate. For it is the motto of this organization to "get" the thief at any cost and at any time. Still, it had not deterred the burglar in this instance.

"I know people are going to think it is a fake burglary," exclaimed Schloss, a stout, prosperous-looking gem broker, as we introduced ourselves. "But over two hundred thousands dollars' worth of stones are gone," he half groaned. "Think of it, man," he added, "one of the greatest robberies since the Dead Line was established. And if they can get away with it, why, no one down here is protected any more. Half a billion dollars in jewels in Maiden Lane and John Street are easy prey for the cracksmen!"

Staggering though the loss must have been to him, he had apparently recovered from the first shock of the discovery and had begun the fight to get back what had been lost.

It was, as McLear had intimated, a most amazing burglary, too. The door of Schloss' safe was open when Kennedy and I arrived and found the excited jeweler nervously pacing the office. Surrounding the safe, I noticed a wooden framework constructed in such a way as to be a part of the decorative scheme of the office.

Schloss banged the heavy doors shut.

"There, that's just how it was—shut as tight as a drum. There was absolutely no mark of anyone tampering with the combination lock. And yet the safe was looted!"

"How did you discover it?" asked Craig. "I presume you carry burglary insurance?"

Schloss looked up quickly. "That's what I expected as a first question. No, I carried very little insurance. You see, I thought the safe, one of those new chrome steel affairs, was about impregnable. I never lost a moment's sleep over it; didn't think it possible for anyone to get into it. For, as you see, it is completely wired by the Hale Electric Protection—that wooden framework about it. No one could touch that when it was set without jangling a bell at the central office which would send men scurrying here to protect the place."

"But they must have got past it," suggested Kennedy.

"Yes—they must have. At least this morning I received the regular Hale report. It said that their wires registered last night as though some one was tampering with the safe. But by the time they got around, in less than five minutes, there was no one here, nothing seemed to be disturbed. So they set it down to induction or electrolysis, or something the matter with the wires. I got the report the first thing when I arrived here with my assistant, Muller."

Kennedy was on his knees, going over the safe with a fine brush and some powder, looking now and then through a small magnifying glass.

"Not a finger print," he muttered. "The cracksman must have worn gloves. But how did he get in? There isn't a mark of 'soup' having been used to blow it up, nor of a 'can-opener' to rip it open, if that were possible, nor of an electric or any other kind of drill."

"I've read of those fellows who burn their way in," said Schloss.

"But there is no hole," objected Kennedy, "not a trace of the use of thermit to burn the way in or of the oxyacetylene blowpipe to cut a piece out. Most extraordinary," he murmured.

"You see," shrugged Schloss, "everyone will say it must have been opened by one who knew the combination. But I am the only one. I have never written it down or told anyone, not even Muller. You understand what I am up against?"

"There's the touch system," I suggested. "You remember, Craig, the old fellow who used to file his finger tips to the quick until they were so sensitive that he could actually feel when he had turned the combination to the right plunger? Might not that explain the lack of finger prints also?" I added eagerly.

"Nothing like that in this case, Walter," objected Craig positively. "This fellow wore gloves, all right. No, this safe has been opened and looted by no ordinarily known method. It's the most amazing case I ever saw in that respect—almost as if we had a cracksman in the fourth dimension to whom the inside of a closed cube is as accessible as is the inside of a plane square to us three dimensional creatures. It is almost incomprehensible."

I fancied I saw Schloss' face brighten as Kennedy took this view. So far, evidently, he had run across only skepticism.

"The stones were unset?" resumed Craig.

"Mostly. Not all."

"You would recognize some of them if you saw them?"

"Yes indeed. Some could be changed only by re-cutting. Even some of those that were set were of odd cut and size—some from a diamond necklace which belonged to a—"

There was something peculiar in both his tone and manner as he cut short the words.

"To whom?" asked Kennedy casually.

"Oh, once to a well-known woman in society," he said carefully. "It is mine, though, now—at least it was mine. I should prefer to mention no names. I will give a description of the stones."

"Mrs. Lynn Moulton, for instance?" suggested Craig quietly.

Schloss jumped almost as if a burglar alarm had sounded under his very ears. "How did you know? Yes—but it was a secret. I made a large loan on it, and the time has expired."

"Why did she need money so badly?" asked Kennedy.

"How should I know?" demanded Schloss.

Here was a deepening mystery, not to be elucidated by continuing this line of inquiry with Schloss, it seemed.